This invention deals with the discovery that certain materials can be added to durable curable silicone rubbers to prevent noise build-up from friction caused when a shaft turns in a shaft seal.
With the advent of powered mechanical drive shafts and the necessary lubrication to keep such shafts friction free, there was developed shaft seals to keep the lubrication from leaking away from the shaft. These early shaft seals took the form of packings rather than coherent forms and often required repacking, very often resulting in down time for the machine containing such shafts.
Later on, coherent, one-piece shaft seals were developed and were made from organic rubbers and fillers. These organic rubbers were susceptible to degradation by the lubrication products and the breakdown products of such lubricants caused by long periods of use.
Producers then switched to the more durable silicone rubbers because they were essentially resistant to many lubricants and their degradation products and were physically tougher than most organic rubbers.
The silicone rubbers, however, has a slight disadvantage, in that, they tend to cause noise when they are in contact with a moving part, such as a shaft, because of friction between the silicone rubber and the shaft. The friction between the shaft seal and the shafts turning face will generate noise after being in use a long period of time. The abrasion caused thereby will spread over the gap between the shaft's turning face and the seal which will eventually result in an oil leak.
There has now been found a way to reduce or eliminate the noise made by a moving part against a silicone rubber seal.